Salvador J. Peris

Distribution of introduced and native fish in Patagonia (Argentina): patterns and changes in fish assemblages

The interaction between native fishes and salmonids introduced in Patagonia at the beginning of the 20th Century, developed at the same time as the environmental change. The phenomenon of global warming has led to the formulation of predictions in relation to changes in the distribution of species, in the latitudinal dimension, both at intralacustrine, or small streams levels. The aim of the present work includes three main objectives: a) to compose a general and updated picture of the latitudinal distribution range of native and alien fishes, b) to analyze the historical changes in the relative abundance of Percichthys trucha, Odontesthes sp., and salmonids in lakes and reservoirs, and c) to relate the diversity and relative abundance of native and salmonid fishes to the environmental variables of lakes and reservoirs. We analysed previous records and an ensemble of data about new locations along the northern border of the Patagonian Province. We compared current data about the relative abundance of native fishes and salmonids in lakes and reservoirs, with previous databases (1984–1987). All samplings considered were performed during spring-summer surveys and include relative abundance, as proportions of salmonids, P. trucha, and Odontesthes sp. For the first time, we found changes in fish assemblages from twenty years back up to the present: a significant decline in the relative abundances of salmonids and an increase of P. trucha. We studied the association between the diversity and relative abundance of native and salmonid fishes and the environmental variables of lakes and reservoirs using Canonical Correspondence Analysis. Relative abundance showed mainly geographical cues and the diversity relied largely on morphometric characteristics. Relative abundance and diversity seem to have a common point in the lake area, included into the PAR concept. Native abundance and alien diversity were negatively related with latitude. Greater native diversity was observed in lakes with high PAR compared with salmonids. Historical changes such as southward dispersion, relative abundance changes, and geographical patterns for relative abundance and diversity are basic concepts needed not only in future research but also in management design for Patagonian fish populations.

Distribution, abundance and density of the wild boar on the Iberian Peninsula, based on the CORINE program and hunting statistics

Abstract. Wild boar population size in the Iberian Peninsula was estimated using hunting bag statistics from Spain and Portugal. Density was estimated assigning the wild boar population size to the “potential resources” or suitable habitats categorized by their importance to provide food and/or shelter to wild boars. Land uses were selected from CORINE, the EU database for land cover, using scientific literature and statistical significance for wild boar presence from published data. The hunting bag was 176245 and 15167 in Spain and Portugal, respectively. The average density was 0.373/km2 (min 0.014-max 2.22) in Spain and 0.13/km2 (min 0.00048-max 1.99) in Portugal, being 0.31/km2 (0.00048-2.22) over the entire Peninsula. Statistical analysis showed that wild boar presence was significantly (p < 0.05) associated to thirteen of the seventeen CORINE land uses selected. Agro-forestry, moors and heathland land use were not statistically significant but were included in the model due to their biological importance. Suitable habitats and distribution of wild boar were mapped for the Iberian Peninsula. This approach is a preliminary step intended to be useful in environmental management and animal health.

Factors influencing wolf Canis lupus roadkills in Northwest Spain

Roadkill is one of the most prominent causes of wildlife mortality. Much research effort has focussed on collisions with ungulates because of traffic safety. However, studies about large carnivore roadkills are scarce despite vehicles being a main cause of mortality. The absence of studies can be explained in part because of difficulties in obtaining sufficient sample sizes. We collected data from locations of 82 wolf roadkill sites in the Castilla y León Region, northwest Spain. We evaluated different models to characterise collision localities using logistic regressions with corrections for rare events. The best models included traffic and human disturbance parameters. Landscape variables did not improve predictive power. Fencing was a decisive key predictor; roadkill was proportionally higher along fenced highways than on similar major roads that lacked fences. Wolf–vehicle collisions were more common in agricultural areas, although wolf densities were lower in these zones. Both the higher density of important roads and a greater proportion of roaming wolves on the plateau may explain this pattern.

Habitat associations of small mammals in farmed landscapes: implications for agri-environmental schemes

The small mammal community in 21 localities of north-western Spain was evaluated in the light of land use composition. The two geomorphologic categories characterising the study area, the main use of the land (arable/pastoral) and main crop types of each sampling locality were used as potential predictors of the relative abundance of five common small mammal species. The Common vole, Microtus arvalis showed a weak relationship with land uses, probably due to the recent colonisation process this species experienced in the study area. The relative abundance of the Algerian mouse, Mus spretus and the Lusitanian pine vole, Microtus lusitanicus was best explained by models built at the broadest regional scale, the former being more abundant in the eastern area, the latter in the western area. The Greater white-toothed shrew, Crocidura russula showed a positive relationship with grassland coverage, whilst the Wood mouse, Apodemus sylvaticus benefited from increasing proportions of fallow lands within the landscape. These two species are then expected to respond positively to those agri-environmental schemes including the increase of fallows and grassy vegetation within the arable landscape (EU recommendations). However, further efforts are needed to predict, at least qualitatively, the response of other small mammal species to the changing farmed landscape. This is especially true for two endemic species occurring at this area: the Cabrera vole, Microtus cabrerae and the Lusitanian pine vole, and for which this kind of information is almost absent.

Use of passages across a canal by wild mammals and related mortality

From 1993–1998, we monitored a 24.1-km long concrete water canal in northern Spain for drowned mammals. Along the canal, 14 concrete bridges and 9 small bridges permitted crossing by humans and livestock. Our objective was to test whether those bridges could be used as passages for wild animals to prevent drowning. We used tracks recorded in sand on bridges to identify species passing. Of the bridges, 65% were used by wild mammals; the 9 small bridges accounted for 57% of crossings by wild animals. Wild and domestic canids (Canis lupus, C.l. domesticus, Vulpes vulpes) were the main users (85%), followed by wild ungulates (mainly wild boar, Sus scrofa) at 71% of the crossings. Proximity to a mountain slope did not increase crossing in deer species, but did not hinder wild boars, foxes and wolves from doing so. Up to 88.1% of the wild mammalian species selected passages that were close to scrubland or forest. Of the drowned animals observed, 70% were dogs and livestock. More roe deer (Capreolus capreolus) drowned than other species, and 73% drowned between April and October. Throughout the year, 6.5% of wild boars fell into the canal . Foxes were the main species crossing the canal, but accounted for only 2.1% of drowned species. We recommend that the following action should be taken to reduce drowning: (1) bridges that are simpler and rustic in design should be constructed and (2) water catchments should be dug into the forest to provide water, so that animals do not need to use the canal as a water source or need to cross it to reach the river.

Intraspecific nest parasitism in the Spotless Starling Sturnus unicolor

Intraspecific nest parasitism in two colonies of Spotless Starling Sturnus unicolor breeding in nestboxes was studied in central Spain from 1991 to 1994. Nests were monitored regularly and three criteria were used to detect nest parasitism: the appearance of more than one egg per day during the laying period of the host; the appearance of an egg after the start of incubation; eggs with unusual shape or pigmentation. The proportion of parasitized nests in first clutches (37%) was twice that of intermediate (19%) or second (20%) clutches in colony B, whereas parasitism occurred in first (35%) and intermediate (12%) but not in second clutches in colony A. Most clutches (52–70%) were parasitized during the hosts laying period and received one parasitic egg. In 10% of the parasitized clutches in colony B, one of the hosts eggs disappeared on the day the parasitic egg was added, suggesting that the parasitic female removed this egg. Although parasitism increased clutch size significantly, it led to a decrease in host breeding success, mainly through the removal of eggs and the loss of host nestlings and the survival of parasitic chicks. Observations suggested that parasitic females were young individuals without their own nests and/or those whose breeding attempt had been disrupted while laying in their own nest.

Status of the avifauna of San Rafael National Park, one of the last large fragments of Atlantic Forest in Paraguay

Summary We provide new information on all birds known from San Rafael National Park, Paraguay. Ornithological records from the period 1997 to 2006 have been reviewed, adding 112 new species to the reserve’s avifauna. We provide data on the presence of 405 species in seven basic habitats types, and on their relative abundance. Biogeographically, San Rafael has a mixed avifauna, consisting of 70 Atlantic Forest endemic species, two Mesopotamian Grassland endemics, and many with a wider distribution in South America. At least 12 species are threatened and 16 nearthreatened, including important populations of Dryocopus galeatus, Platyrinchus leucoryphus, Alectrurus tricolor and Xanthopsar flavus. We provide brief comments on records of these 28 species within the study site. The avifauna of the reserve is one the most important in Paraguay, due to its high diversity and endemism. At the same time, it is under great threat and its viability is at risk unless urgent actions are taken. Fragmentation of the Atlantic Forest in Paraguay has left the San Rafael block almost totally isolated from other forests. The degradation of its forests through selective logging and clearance for agriculture still has severe impacts, as do hunting and frequent fires in grasslands and forests. Unfortunately, the legal situation of the National Park is extremely precarious, creating great uncertainty and problems for its conservation.

Food resources and reproductive output of the Austral Parakeet (Enicognathus ferrugineus) in forests of northern Patagonia

Abstract Assessing use of resources across resource gradients and over time is necessary for determining factors that influence the natural distribution of birds. We analysed the pattern of availability of food resources, the use of food resources and the influence of food availability on reproduction and demography for the Austral Parakeet (Enicognathus ferrugineus) in two southern temperate forests of Argentine Patagonia. The abundance of Austral Parakeets in Nothofagus pumilio forests co-dominated by Araucaria araucana was generally higher and fluctuated more than abundance of populations in monospecific N. pumilio forest. This appears to be related to A. araucana providing a larger but more variable food resource. Austral Parakeets responded quickly to changing availability of resources by modifying their diet if alternative food resources were available, and reproductive success also increased when seed availability was high. We found mixed forests to be a unique and important habitat for Austral Parakeets in the northern part of their range, and conservation management should recognise this special role that mixed N. pumilio—A. araucana forests play in Austral Parakeet ecology.

Reproductive phenology and breeding success of the monk parakeet (Myiopsitta monachus monachus) in Argentina

The breeding biology of the Monk Parakeet (Myiopsitta monachus monachus) was studied in Punta Blanca, central Argentina (34° 56’ S, 57° 39’ W). Observations on 9 communal nests (13 breeding chambers) were made dur‐ing 1988 and 1989. The median date of the first egg for each year was Hand 31 October (the median for 2 years was 16 October). Clutch size ranged from 5 to 12 eggs, averaging 6.9. Incubation took 23.6 days and hatching was asynchronous. Mean hatching success for clutches was 52.2%. Only 17% of the nestlings fledged. Only 8.9% of the total eggs laid resulted in fledglings. Predation by Opossums (Didelphis) and Black Rats (Rattus) was the main cause of mortality at nests (82%), but 17.9% of the nestling mortality was due to intraspecifics attacks, including sibling aggression.

Consumption of Larvae by the Austral Parakeet (Enicognathus ferrugineus)

Abstract We report observations of the Austral Parakeet (Enicognathus ferrugineus) feeding on larvae in the northern part of its distribution in the austral temperate forests of Argentine Patagonia during the pre- and post-reproductive seasons. Larvae consumed were Aditrochus fagicolus (Chalcidoidea: Pteromalidae) in leaf galls of Nothofagus pumilio (79 observations), larvae from Homoptera, Lepidoptera, and Diptera in seed galls of N. pumilio (12 observations), and larval Nemonychidae (Coleoptera) in male cones of Araucaria araucana (69 observations). Our observations suggest Enicognathus ferrugineus could be more insectivorous than previously thought, perhaps to help meet their demand for high-quality food during the pre- and post-reproductive seasons.